ENGLAND'S preparations for the first Test continue to be overshadowed by the uncertainty about captain Michael Vaughan's knee injury.

It was expected Vaughan - now rated "very doubtful" - would discover yesterday whether the suspected cartilage damage he suffered in his right knee would stop him facing Pakistan on Saturday, or even end his tour.

Instead, with only two days to go before the start of the three-match series in Multan and three days after Vaughan collapsed to the ground while batting against Pakistan A, England's medical experts are still unable to give an answer on the captain's fate.

Twenty-year-old Essex batsman Alastair Cook was called up yesterday as batting cover for Vaughan - while the selectors also announced veteran off-spinner Shaun Udal will be retained after the Test series for the one-day internationals which follow, for which Worcestershire all-rounder Kabir Ali has been called up.

The England and Wales Cricket Board issued a statement explaining the reasons for keeping Vaughan on tour for now.

Series

It read: "Michael will remain with the squad and the medical team will continue to monitor his progress closely. He is rated very doubtful for the first Test in Multan, and his availability for the second and third Test matches will be reassessed in due course."

Vaughan's previous scans date from an operation in 2002 on torn cartilage and a second injury last year which ruled him out of the Lord's Test against New Zealand but did not prevent him playing in the rest of the series.

Udal, probably set for a Test debut this weekend at the age of 36, confirmed no one is assuming anything.

"Michael hasn't been written out of the equation yet. He might yet still be fit enough to play, which would be fantastic," he said.

"If he isn't we have a very able deputy in Marcus (Trescothick) and some quality back-up."

While the captain is left to ponder whether he will regain fitness in time, Cook was digesting news of his call-up.

"I didn't expect this in my wildest dreams," he said. "I think if Owais Shah or Robert Key had been fit one of them would have been going out there. But I am absolutely thrilled.